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    <title>Document</title>
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    <script>
      let str = `33a 3333b 333c 33333d e 3y`;
      // 取反

      // console.log(str.match(/3333[a-z]/g));
      console.log(str.match(/3{4}[a-z]/g));
      console.log(str.match(/3{2,5}[a-z]/g));
      console.log(str.match(/3+[a-z]/g)); // {1,}
      console.log(str.match(/3?[a-z]/g)); // {0,1}
      console.log(str.match(/3*[a-z]/g)); // {0,}
    </script>
  </body>
</html>
